The present invention relates generally to gas turbine engines, and, more particularly, to temperature and pressure sensors for measuring compressor inlet temperature and pressure.
In certain aircraft and aero-derivative gas turbine engines sensors are used to measure air temperature and pressure at the inlet to the compressor. Accurate measurements of the inlet temperature and pressure are critical, because the measurements are used for establishing control of the variable geometry of the stators in the compressor. In some operating conditions of aircraft engines, ice may accumulate on the inlet temperature and pressure sensor. Ice accretion interferes with the accuracy of the temperature and pressure readings provided by the sensors, and release of accumulated masses of ice into the compressor may cause damage to compressor blades.
A heat pipe is a known heat transfer device utilizing an evaporation and condensation cycle for transferring heat from a hot or heat input region to a cold or heat output region of the device with minimum temperature drop. One type of heat pipe comprises a closed, pressurized container within which is a layer of wicking material extending from the heat input region to the heat output region and saturated with a compatible vaporizable liquid. The volume interior to the closed, pressurized container is pressurized to a fixed pressure that sets the saturation temperature of the liquid. Selection of the vaporizable liquid is based upon its known vaporization and condensation characteristics at its saturation pressure and temperature, particularly its vaporization and condensation characteristics at the pressure selected for the closed, pressurized container. The temperature typical of the environment within which it is to be used are taken into account is selecting the container, liquid and wicking material. Heat applied to the heat input region of the closed, pressurized container vaporizes the liquid. The resulting vapor moves to the heat output region of the container, where the liquid transfers heat to the wall of the container and condenses to its liquid state. The condensed liquid is returned to the heat input region by capillary action in the wicking material. The heating and condensation cycle is repeated continuously to maintain a nearly constant temperature within the heat pipe and a consistent temperature relationship between the heat input region and heat output region.